A terbium-based time-resolved luminescent probe for sulfide ions mediated by copper in aqueous solution

Abstract

A novel Tb(III) complex-based time-resolved luminescent probe, BBPNA-(DO3A-Tb3+)2 (L), was designed and synthesized for the recognition of Cu2+ and sulfide ions in aqueous solutions. The luminescent probe L was efficiently quenched by Cu2+ and displayed “on–off” type luminescence change towards Cu2+. Once combined with Cu2+ to form the non-luminescent L–Cu complex, the L–Cu complex could serve as an “off–on” probe for sulfide ions due to the high affinity of sulfide ions towards Cu2+. In the presence of S2−, the L–Cu complex reacted with S2− to cause the release of the Cu2+ and turn on the luminescence of L again. The rebuilding of luminescence was highly selective to S2− over other common anions, which allowed L function as an “on–off–on” probe for Cu2+ and S2− alternately. Especially, the luminescence lifetime of the probe was about 1.91ms, much longer than most organic fluorophores. Due to the long luminescence lifetime of the probe L, the probe could be used for time-resolved luminescence measurements to eliminate the interferences from autofluorescence and scattering lights and significantly to improve the signal-to-noise for detection.